Sizing and cutting apparatus

ABSTRACT

Apparatus for sizing and bandsaw cutting of meat, wherein the pieces of product to be cut are mounted in a magazine for rotation around a path which intercepts a sensor means and a bandsaw, with the pieces resting on a vertically adjustable horizontal table, the sensor means being disposed in the surface of the table to sense the area of the lower face of the product, thereby to enable automatic adjustment of the level of the table so that the bandsaw cuts a slice of product of required size from the lower end of the pieces.

FIELD OF THE INVENTION

This invention concerns sizing and cutting apparatus for handlingirregularly shaped products such as meat whereby the product is to becut into uniform pieces. The invention is not however limited to usewith meat.

BACKGROUND TO THE INVENTION

As discussed in UK Patent No. 2149650, with certain products,particularly meat, it is difficult to keep the size of cut portionsconstant. This is particularly the case when dealing with a product suchas pork chops.

The earlier patent describes apparatus for cutting or sawing a productsuch as a side of pork into uniformly sized portions which includesmeans for determining the area of the end face of a region of theproduct from which pieces are to be cut or sawn, computing means havingstored therein a numerical density value for the material to be cut anda numerical weight value corresponding to the desired weight per cutpiece, the computing means being adapted to compute from the measuredarea of the end face, the depth of the cut required to obtain a piece ofthe desired weight. Means is provided for adjusting the depth of cutusing the computed thickness value to obtain pieces of the desiredweight and there is further means enabling correction of the numericaldensity value in the computing means by sampling the weight of a cutpiece.

The apparatus described in the aforementioned patent specificationincludes a closed track around which a meat carrying platform moves witha piece of meat on the platform. A bandsaw cutter is located at oneposition around the track operating vertically and a guide deflects thecut slice onto a check weighing apparatus from where the checked piecescan be loaded into a bin or onto a conveyor. The movement of theplatform around the track is controlled by a drive unit which itself iscontrolled from a control centre and the position of the bandsawrelative to the end face of the meat is also controlled by another driveunit which is computer controlled.

At a position remote from the bandsaw is located and X Y scanning devicefor producing an area signal corresponding to the area of the piece ofmeat which is next to be cut by the bandsaw.

Whilst such apparatus can be made to function at moderate speeds, highspeed operation is limited due to the considerable spacing between thescanner and the bandsaw. Although it is possible to utilise the delaybetween the scanner and the bandsaw for the purpose of computing thedepth to which the piece is to be cut, with even low speed computingtechniques, the time period is excessive and the throughput of themachine is therefore considerably limited.

It is one object of the invention to provide a machine which whilstcutting to the same degree of accuracy will nevertheless allow a greaterthroughput of cut product.

It is a further object of the invention to apply the sizing techniquedescribed in the aforementioned patent No. 2149650 to a bandsaw in whichthe cutting is effected in a horizontal plane rather than a verticalplane.

It is a further object of the invention to provide a machine for cuttingconstant volume pieces of a product.

It is a further object of the invention to provide a sizing and cuttingapparatus for removing constant volume pieces of product by ahorizontally acting bandsaw in which the thickness of the material to beremoved by the bandsaw is adjustable at high speed in response to anelectrical signal relating to the area of the product concerned so as toenable variations in thickness of cut to be made "on the fly", to followchanges in cross-sectional size and shape of the product as pieces areremoved therefrom, to enable pieces of constant volume to be deliveredat the output of the machine.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, in apparatus forsizing and cutting a product into uniformly sized portions, the productto be cut is mounted in a magazine by which it can be rotated around acircular path which intercepts at one point the horizontal section of abandsaw and at another point a sensor from which an electrical signalcan be computed which describes the area of the lower end face of theproduct, wherein the sensor lies in the horizontal surface on which thecut face of the product slides as the product is rotated around thecircular path by the magazine.

Conveniently the sensor comprises a linear array of transmitters anddetectors which may be addressed in sequence or whose outputs may besummed and the resulting analogue signal sampled as the product passesover the line of detectors, to effect a linear scanning of the array andwherein the presence of product immediately above the array causestransmitted energy to be reflected towards the detectors. The outputstate of the latter thus varies depending on whether product isimmediately above the array or not and an area signal can be computed byintegrating the electrical signals received from scanning the array ofdetectors as the product passes thereover.

The magazine may carry one or more large pieces of product from whichthe smaller pieces are to be cut and typically these are circularlyarranged around the magazine so as to be presented one after another inturn first to the scanning sensor and then to the cutting blade of thebandsaw.

Typically the apparatus includes conveyor means for removing cut piecesfrom the path of the magazine to enable the material to drop down topresent a fresh piece of product for cutting by the bandsaw on the nextpass.

According to another aspect of the invention, the surface on which thelower end faces of the large pieces of product travel as the magazinerotates is integral with a table assembly which is movable relative tothe magazine and at least the horizontal section of the bandsaw so as toadjust the depth of the product below the blade and therefore thethickness of the slice of material which will be removed by the cuttingaction of the blade.

Preferably drive means is provided for adjusting the height of the tableassembly relative to the blade so as to allow for automatic control ofthe thickness of the cut slices and feedback means is provided from acomputer to which area signals are supplied for controlling the depth ofcut and therefore the thickness of the slices removed by the bandsaw. Byensuring that the computation is performed quickly and providing forhigh speed movement of the table assembly in a vertical manner either upor down, and by synchronising the adjustment of the table assembly withthe movement of the magazine, so the height of the table assembly can becorrected between the time taken to scan the end face of the product andthe arrival of the product at the blade so that precisely the correctthickness of product is removed by the cutting blade so as to maintainthe volume of each piece of cut product substantially constant.

Typically the table assembly is raised or lowered by means of arotatable lead screw typically driven by an electric motor, preferably aservo motor.

For particularly high speed operations, the mass of the table assemblymay be matched by two or more pneumatic jacks acting against theunderside of the table assembly and operated from a source ofpressurised air or gas so as to provide an upward force on the tableassembly which is never more than the downward force due to gravity ofthe table assembly. In this way the effective mass of the assembly isreduced to a very small amount and the energy required to accelerate thetable assembly is significantly reduced thereby enabling the tableassembly to be accelerated and decelerated at a higher rate with a givermotor than would otherwise be the case.

The pneumatic jacks are preferably provided with air or gas under aconstant pressure and typically venting means is provided to enable thejacks to collapse rapidly so as to follow any downward movement of thetable without exerting undue upward force on the table during itsdownward movement.

The venting means is preferably pressure responsive.

According to a further aspect of the invention, display means isprovided for indicating a computed value for the weight of each cutslice determined by the depth of cut and area of the end face of thepiece concerned. Conveniently the display means is a cathode ray tube.

If a check weighing device is provided at the outlet of the machine, asignal from the check weigher may be also displayed to indicate in thesame display the actual weight measured for comparison purposes.

During high speed operation, the numerical values displayed maycorrespond to an average of the computed weight of cut pieces and anaverage of the actual weight of cut pieces passing over the checkweigher.

The check weigher may be incorporated into the apparatus and form partof the apparatus or may be separate therefrom.

Since it is important to know precisely where each piece of product isduring the circular path defined by the rotation of the magazine, thedrive for the magazine preferably includes an encoder for circularlydefining the position of the magazine relative to the cutting blade andthe line of sensors for measuring the area.

Electrical signals for display on the display means may be derived fromcomputing means which itself is supplied with signals from the scannerand the computing means may be located within the machine or may beremotely located and connected thereto by cables.

The servo motor is conveniently mounted remote from the lead screw jackand the latter is preferably driven by means of a toothed belt drivefrom the servo motor.

Preferably a powerful electromagnetic brake such as a disc brake isattached to the lead screw to arrest the motion of the latter when thedesired height of the table assembly has been achieved.

Preferably vertical guides are provided within the machine and rollermeans is provided on the table assembly to cause the latter to move in atrue vertical manner relative to the overall assembly of the machinewith the rollers running vertically up and down the guides.

In a preferred embodiment of the invention, the radial array ofinspection windows comprising the scanner is arranged at approximately120° in advance of the cutting blade of the horizontal section of thebandsaw, when viewed in the direction of travel around the circular pathdetermined by the rotation of the magazine.

The invention will now be described, by way of example, with referenceto the accompanying drawings, in which:

FIG. 1 is a perspective view of a meat cutting apparatus embodying theinvention;

FIG. 2 is a perspective view to an enlarged scale of the meat cuttingstation of the apparatus shown in FIG. 1 with the main machine doorrotated inboard to permit loading and unloading;

FIG. 3 is a view of the meat cutting station from above with the rotarymagazine and door removed to show diagrammatically the passage of piecesof meat around the meat cutting station over the sizing scanning windowand past the cutting blade of a bandsaw to exit on the deliveryconveyor;

FIGS. 4a and 4b show the component parts of one of the elements of thelinear scanning window and illustrate how the presence of meat producesa reflection to a receiver unit;

FIG. 5 is a perspective view to an enlarged scale of the deliveryconveyors of the machine shown in FIG. 1;

FIG. 6 is a perspective view in the general direction of arrow VI ofFIG. 5 and shows the guide and roller mechanism by which the movabletable is constrained to move upwardly and downwardly in a verticalmanner;

FIG. 7 is an elevation of the exit end of the machine shown in FIG. 5with side panels removed to show part of the internal workings of themachine;

FIG. 8 is a similar elevation this time viewed in the direction of arrowVIII of FIG. 7, again with side panels of the machine removed showingthe two pneumatic cushions and lead screw drive for the movable table,and

FIG. 9 is a part sectioned view, to an enlarged scale, through the leadscrew table elevating mechanism and drive means therefor.

DETAILED DESCRIPTION OF THE DRAWINGS

As shown in FIG. 1, meat cutting and sizing apparatus is housed within ahousing 10 which includes a control panel 12 containing a televisionscreen 14 for displaying information relating to the process, a meatcutting station access to which can be gained through a first door 16and a second door 18, both of which are shown in their closed positionand which include viewing windows 20, 22, 24 and 26. Meat pieces cutfrom large pieces of meat located within the cutting station exit on aproduct delivery conveyor 28 and pieces which are of insufficientthickness, such as ends, are removed by conveyor 30.

FIG. 2 shows the interior of the meat cutting station and is accessibleby rotating the door 18 to the internal or inboard position shown inFIG. 2. Suspended within the cabinet 10 is a rotatable magazinegenerally designated 32 having a vertical shaft 34 on which it iscarried and which is rotated by a drive motor (not shown) which may beat the top of the housing or located below the cutting station asdesired. An encoder unit is shown at 36. The encoder 36 provideselectrical signals indicating the rotational position of the magazine.Side panels such as 38 are removable from the magazine by unhitchingfrom top and bottom plates attached to the shaft 34, to enable meatcarcass or other like material to be mounted thereon and positionedwithin the magazine.

On rotation, the lower end of a piece of meat carried by the magazinepasses over a plate 40 containing a line of apertures 42 forming ascanning or viewing window (to be described later) and thereafter ismoved towards the horizontal section 44 of a bandsaw so that thelowermost part of the meat which is resting on the flat table 46 isremoved from the remainder of the material by the saw blade, and isimmediately drawn away from the remainder of the meat by the movement ofa conveyor the slats of which are shown at 48 and which moves in thedirection of the arrow 50. The conveyor describes a generally circularpath and then exits from the meat cutting station in a straight line at52 and delivers cut pieces of meat to a collecting bin or the like.

The principle of operation is perhaps best seen with reference to FIG. 3in which the magazine and the door shown in FIG. 2 have been removed andin which the meat cutting station is viewed axially from above. A numberof pieces of meat are shown circularly arranged around the shaft 34 asat 54, 56, 58 etc and the direction of rotation is shown by the arrow60. The piece of meat 58 is shown approaching the horizontal section 44of the bandsaw and as the magazine rotates the meat through the saw, thelowermost region of the meat is removed from the remainder and drawnaway on the conveyor 48 to leave the machine along the exit path 52.

Prior to reaching the blade 44, the bottom of each large piece of meatcarried by the magazine will have dropped onto the flat upper surface 46of the cutting table and in its passage around the circular path willhave passed over the line of elemental inspection windows of thescanning window shown at 42.

The latter is best understood with reference to FIG. 4s 4a and 4b. InFIG. 4a one of the apertures is denoted by reference numeral 62 andbelow the aperture are located a transmitting light emitting diode 64and a semiconductor junction 66 which is sensitive to the incidence ofelectromagnetic radiation thereon. The light emitting diode has asignificant output in the infra-red and the detector 66 is likewiseselected for its sensitivity to infra-red radiation.

By positioning at least the detector 66 below the solid materialsurrounding the window, ambient on the detector is largely shielded fromambient radiation incident on the window. In the absence of anythingabove the window 62, infra-red radiation emitted by the transmittingdiode 64 simply passes through the window 62 and in general is notreflected towards the detector 66.

However, if a piece of meat as at 68 is positioned above the window,some of the radiation from the transmitter 64 is reflected towards thedetector 66 causing the current through the junction of the detector 66to change typically increase and register as an output signal.

By arranging similar pairs of transmitter and detector devices beloweach window along the line of windows 42, the presence or absence ofproduct immediately above each window can be detected by determining thecurrent flowing in the detector junction relating to the windowconcerned. The larger the piece of meat measured in a radial directionalong the length of the line 42, the more of the windows will be coveredby the meat and therefore the larger the number of detector devices suchas 66 which will record a high output current.

It will be seen that the detector is sensitive to reentrant shapes suchas those shown in FIG. 3 at 54 and 56 and will take account of holes inthe cross-sectional shape of the product thereby enabling an accuratemeasure of area to be obtained.

The detector outputs may be summed to produce an output signal whosemagnitude will be proportional to the length of the intersection of thelinear array with the face of the meat. The detectors in turn startingfor example with the radially innermost and moving outwardly and readingeach detector in turn at high speed. By sampling the output signal at ahigh repetition rate, as meat passes over the array so a series ofoutput signals of varying magnitude will be generated which can then beintegrated to give an area signal.

If alternatively the detectors are scanned, so that each detector isaddressed in turn a discrete separate output pulse can be generated ifthe output signal from the detector is sufficiently high, and duringeach scanning of the line of detectors a series of pulses will arise,the number of which will correspond to the length of the array coveredby the product. Counting the number of pulses during the passage of theproduct will give an area value for the product.

In order to take account of the circular movement of the meat over theradially extending line of windows, a correction must be applied to thesignals either before or during the integration of the signals arisingduring the passage of any particular piece of meat over the scanningwindow so as to compensate for the different path length of the meatproduct as between the radially inner and outer ends of the line ofwindows.

FIG. 5 shows the second exit conveyor 70 (previously referred to asconveyor 30) which works in conjunction with the main delivery conveyor52. Conveyor 70 receives portions of meat or other cut product which areof insufficient thickness to be picked up on the main delivery conveyor52 and which are carried around by the magazine on a plough-likeplatform 72 by rotation of the magazine, to be deposited on the exitconveyor 70.

A spoked wheel 74 is provided which can be rotated so as to adjust thetension of the bandsaw. The hub of the wheel 74 extends through a slot76 in the vertical side wall 78 of the table, the top of which isdenoted by reference numeral 46, to enable relative vertical movementbetween the table and the hub 74 to occur. This is necessary sincewhilst the bandsaw is to remain stationary (in a vertical sense), thetable carrying the conveyors 52 and 70 must be capable of movingrelative to the remainder of the machine to adjust the thickness of themeat which is being cut.

One of the uprights of the casing is shown at 80 in FIGS. 5 and 6, andthe separate nature of the table relative to the rest of the casing isperhaps best illustrated in FIG. 6 where the exit ends of the conveyors52 and 70 are seen protruding beyond the upright corner member 80, andthe table assembly generally designated 82, is shown having a roller 84mounted for rotation against one of the vertical surfaces of the cornermember 80, to guide the table assembly 82 as it moves in the directionof the arrows 86 and 88 respectively.

Vertical movement of the table assembly 82 is achieved by means of alead screw to be described in more detail in relation to FIG. 9 andwhich is housed partially within a casing 90 attached to the undersideof the table assembly 82 and partly within a housing 92 which itself issecured to the remainder of the casing 10 and is therefore fixed.

Rotation of the lead screw produces relative movement of the housing 90and 92, and thereby lifts or lowers the table assembly 82.

Drive to the lead screw is transmitted through a toothed belt 94 from aservo motor and encoder assembly 96 and a safety brake 98 is located atthe base of the drive shaft of the lead screw so that the movement ofthe latter can be arrested in an emergency and at the end of eachmovement travel.

The lifting mechanism of the lead screw is shown from a different viewin FIG. 8 but shows better the alignment of the brake 98 with the leadscrew housings 92 and 90 and the position of the servo motor and encoderunit 96.

Within the structure 10 is located an intermediate floor 100 on whichtwo pneumatic jacks 102 and 104 stand. The upper ends of the jacksengage through Nylon (Registered Trade Mark) bushes 106 and 108 with theunderside of a main structural member of the table assembly 82 and thetwo jacks are supplied with air under pressure via high pressure lines110 and 112. The air pressure to the jacks 102, 104 is arranged at alltimes during operation to just balance the weight of the table assembly82 and thereby remove the loading on the screw jack formed by the parts90, 92 and indirectly on the servo motor 96. This enables the latter toaccelerate and decelerate the table assembly 82 at a very high ratewithout overloading and overheating and enables very rapid changes oftable height (and therefore depth of cut) to be achieved, so as toensure that variation in the area of cross-section of a piece of meat orother product as slices are removed, can be followed by appropriatecompensating adjustments in the thickness of the material to be cut, soas to enable substantially constant volume pieces to be delivered to theoutput conveyor 52.

The jacks 102 and 104 are supplied via a constant pressure device whichsupplies air to, or bleeds air from the cylinders, as required, so as tofollow movement of the table assembly 82, and at the same time maintainthe desired weight compensating upward force thereon. By so doing theweight of the table is compensate and this loading which will normallyact in a downward direction through the screw jack, is removed.

It is to be understood that the pneumatic jacks are optional and areonly required where very high rates of acceleration and deceleration arerequired of the table assembly 82 so as to rapidly follow changing areasof cross section. If slower response is acceptable or if the machine canbe momentarily stopped or slowed down so as to enable the table assembly82 to be positioned for the correct height of cut, the need for thejacks is reduced.

FIG. 9 shows the upper housing 90 of the screw jack assembly bolted tothe underside of the table assembly 82 and the lower housing portion 92which is bolted to the main structure of the casing 10 (see FIG. 7 at114 and 116).

Within the lead screw is a drive shaft the lower end of which can beseen at 116 in FIG. 9 and a toothed drive pulley 118 is bushed orotherwise mounted on the shaft 116 to be driven by the toothed belt 94.The belt passes around a drive pulley 120 which is attached to the lowerend of the drive shaft of a servo-motor and encoder unit 96. The latteris housed within a casing 122.

Rotation of the shaft 116 produces relative movement of the two housingparts 90 and 92 and thereby controls the height of the table 82 relativeto the remainder of the structure of casing 10.

A brake denoted 122, but in essence equivalent to the brake 98 shown inFIGS. 7 and 8, is shown mounted below the lead screw, co-axial with theshaft 116, and when applied, the brake prevents further movement of thelead screw and therefore further separation or drawing together of thetwo housing parts 90 and 92. The brake can therefore be used as a safetydevice to prevent the table assembly 82 from being raised too high ormoved too low.

I claim:
 1. Apparatus for sizing and cutting a product into uniformlysized portions, in which the product to be cut is mounted in a magazineby which it can be rotated around a circular path which intercepts atone point a horizontal section of a bandsaw and at another point theoperative field of a sensor disposed in said path from which anelectrical signal can be computed which describes the area of the lowerend face of the product, wherein said sensor is disposed in a horizontalsurface on which the lower end face of the product slides as the productis rotated around the circular path by the magazine, and wherein saidhorizontal surface on which the lower end face of the product slides isintegral with a table assembly which is movable relative to at least thehorizontal section of the bandsaw, so as to adjust the depth of theproduct there below and therefore the thickness of the portion whichwill be removed by the cutting action of the bandsaw.
 2. Apparatusaccording to claim 1, wherein said sensor comprises a linear array oftransmitters and detectors extending radially of said circular path andwhich may be addressed in sequence and whose outputs may be summed andthe resulting analog signal sampled as the product passes over thearray, in order to effect a linear scanning of the array, and whereinthe presence of product immediately above the array causes transmittedenergy to be reflected towards the detectors.
 3. Apparatus according toclaim 1, wherein the magazine is adapted to carry one or more largepieces of product from which said portions are to be cut, the piecesbeing circularly arranged around the magazine in use so as to bepresented one after another in turn to the bandsaw, the apparatus alsoincluding conveyor means for removing cut portions from the path of themagazine to enable them to drop down to present a fresh portion ofproduct for sizing and for cutting by the bandsaw.
 4. Apparatusaccording to claim 1, including drive means for adjusting the height ofthe table assembly relative to the horizontal section of the bandsaw soas to allow for automatic control of the thickness of the cut portionsand feedback means connected to a computer to which area signals aresupplied for controlling the depth of cut and therefore the thickness ofthe portions removed by the bandsaw.
 5. Apparatus according to claim 4,wherein the mass of the table assembly is matched by two or morepneumatic jacks acting against the underside of the table assembly andoperated from a source of pressurised fluid so as to provide an upwardforce on the table assembly which is never more than the downward forcedue to gravity of the table assembly, pressure responsive venting meansbeing provided to enable the jacks to collapse rapidly so as to followany downward movement of the table without exerting undue upward forceon the table during its downward movement.
 6. Apparatus according toclaim 1, including display means for indicating a computed value for theweight of each cut portion determined by the depth of cut and area ofsaid lower end face.
 7. Apparatus according to claim 6, furthercomprising a check weighing device provided at the outlet of themachine, whereby a signal from the check weighing device is displayed toindicate the actual weight measured.
 8. Apparatus according to claim 1,further comprising a drive for the magazine which includes an encoderfor circularly defining the position of the magazine relative to thecutting blade and to the sensor for measuring the area.
 9. Apparatusaccording to claim 1, wherein the sensor comprises a radial array ofinspection windows positioned approximately 120° in advance of thecutting blade of the horizontal section of the bandsaw, when viewed inthe direction of travel around the circular path determined by therotation of the magazine.